An entire brigade, hurrying to the battle, was passing the slope, when Warren literally seized upon them by force of command and rushed the men and their cannon to the crest.
Hood's soldiers were already climbing the slopes, when the fire of the brigade, shell and bullets, struck almost in their faces.

Harry, watching through his glasses, saw them reel back and then go on again, firing their own rifles as they climbed over the rocky sides of Little Round Top.

Again that fierce volley assailed them, crashing through their ranks, and again they went on into the flame and the smoke.
Harry saw the battle raging around the crest of Little Round Top.
Then he uttered a cry of despair.

The Southerners, with their ranks thin--woefully thin--were falling back slowly and sullenly.

They had done all that soldiers could do, but the commanding towers of Little Round Top remained in Union hands, and the Union generals were soon crowding it with artillery that could sweep every point in the field below.
But Sickles himself was not faring so well.